Conduit-clearing pyrotechnic device for remediation of residual explosive contamination

ABSTRACT

A device and method for cleaning a sewer line, or other conduit, storage tank, or other vessel, of explosive material deposited in and/or on an inner wall thereof, includes placing a flexible hose containing a non-explosive pyrotechnic composition within the conduit or vessel, and burning the pyrotechnic composition. According to various embodiments, the non-explosive pyrotechnic composition can be a composition that burns, combusts, or deflagrates, at a rate that enables it to be classified as a D.O.T. class 1.4 explosive posing no significant detonation or blast hazard and that can be shipped to various locations using relatively inexpensive shipping means.

INTRODUCTION

The present teachings relate to a device and method to be used in the break down of an explosive material deposited in or on an inner wall of a conduit or vessel.

SUMMARY

According to various embodiments, a device is provided that includes a pyrotechnic material that can be burned to achieve an inner wall temperature inside a conduit or vessel at or in excess of the break down temperature of an explosive material deposited on the inner wall.

A conduit-clearing pyrotechnic device according to various embodiments can comprise a flexible hose, and a pyrotechnic composition disposed within the flexible hose, the pyrotechnic composition comprising a fuel, an oxidizer, and a binder.

According to various embodiments, a method of cleaning a conduit or vessel is provided that can comprise placing a flexible hose containing pyrotechnic material in a conduit or vessel comprising an explosive material deposited in or on an inner wall there, and burning the pyrotechnic material to achieve an inner wall temperature at or in excess of a break down temperature of the explosive material, to break down the explosive material.

Additional features and advantages of the present teachings will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the present teachings. The objectives and other advantages of the present teachings will be realized and attained by means of the elements and combinations particularly pointed out in the description that follows.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present teachings are exemplified in the accompanying drawings. The teachings are not limited to the embodiments depicted in the drawings, and include equivalent structures and methods as set forth in the following description and as would be known to those of ordinary skill in the art in view of the present teachings. In the drawings:

FIG. 1 shows a conduit-clearing pyrotechnic device, according to various embodiments.

FIG. 2 shows the conduit-clearing pyrotechnic device of FIG. 1 disposed in a conduit, according to various embodiments.

DESCRIPTION OF VARIOUS EMBODIMENTS

A conduit-clearing pyrotechnic device, according to various embodiments, can comprise a flexible hose, and a pyrotechnic composition disposed within the flexible hose, wherein the pyrotechnic composition can comprise, for example, a fuel, an oxidizer, and a binder. The flexible hose containing the pyrotechnic composition can be placed inside of a conduit such as a sewer line or inside a vessel such as an above ground or underground storage tank, that comprises an explosive material deposited in or on an inner surface or inner wall thereof. The explosive material or residue deposited in or on the inner wall of the conduit or vessel can have a break down temperature, and the pyrotechnic material along with the flexible hose containing the pyrotechnic material can be burned in order to achieve an inner wall temperature at or in excess of the break down temperature. The break down temperature of the explosive material is the temperature at which a chemical change in the composition of the explosive material occurs, for example, the temperature at which the explosive material ignites, combusts, explodes, deflagrates, oxidizes, reduces, decomposes or otherwise breaks down. Exemplary break down temperatures are shown in the table below.

Explosives Break Down Temperatures Material Melting Point Deflagration Temperature Tri Nitro Toluene 80.9° C./178° F.  281°-300° C./537°-572° F. Hexahydro-1,3,5- 200° C./392° F. 260° C./500° F. Trinitro-1,3,5-Triazine Pentaerythritol 141.3° C./286° F.  201° C./394° F. Tetranitrate Nitro-Gylcerine 13.5° C./56.3° F. 222° C./432° F. Nitrocellulose 135° C./275° F. 170° C./338° F. Composition B 192° C./378° F. 278° C./532° F.

Referring to FIG. 1, a conduit-clearing pyrotechnic device 30, according to various embodiments, can comprise a flexible hose 32 that contains a pyrotechnic composition 50 and an ignition mechanism 42. The ignition mechanism 42 can extend inside the flexible hose 32 and can be in contact with the pyrotechnic composition 50 within the flexible hose, or it can be spaced away from the pyrotechnic composition (not shown). The ignition mechanism 42 can extend inside the flexible hose 32 along a portion of the length or along the entire length of the flexible hose 32.

The flexible hose 32 can include a plurality of pores or holes 34 through the wall thereof. The flexible hose 32 can include or consist of a regular garden hose or a soaker garden hose, for example. The pyrotechnic composition 50 can comprise granules 36 or a powdered material. The size of a pellet or granule can be any suitable size and can range, for example, from about 1 mm or less to about 10 cm in length. Other ranges for the length can be, for example, from about 2 mm to about 5 cm, from about 5 mm to about 3 cm, or from about 1 cm to about 2 cm. The width, thickness, and/or diameter of the pellets or granules can be, for example, from about 1 mm to about 2 cm, from about 5 mm to about 3 cm, or from about 1 cm to about 2 cm. A first end cap 38 at one end of the flexible hose 32 can be provided to hold the pyrotechnic composition 50 in the flexible hose 32. The first end cap 38 can comprise a plastic or wax material, for example, and can include a hole therethrough for passage of the ignition mechanism 42. The opposite end 40 of the flexible hose 32 can also be provided with a second end cap 39 that can also be provided to hold the pyrotechnic composition 50 in the flexible hose. The pyrotechnic composition according to various embodiments can comprise a fuel and can optionally also comprise an oxidizer and/or a binder. The pyrotechnic composition can be formulated such that it can be classified by the Department of Transportation (D.O.T.) as a division 1.4 explosive with no significant blast hazard. A classification by the D.O.T. as a division 1.4 explosive would allow the shipment of the pyrotechnic composition using relatively inexpensive shipping methods.

The pyrotechnic composition can be a material that is capable of combustion when correctly initiated, to provide a special effect. The pyrotechnic composition can be a mixture of fuel and oxidizer, and can burn, but unlike an explosive, does not detonate. The burn rates for pyrotechnic compositions are 2 to 3 orders of magnitude less than the detonation velocity of an explosive. The burn rate of the pyrotechnic composition can vary greatly depending, for example, on the composition, compaction, and configuration. The special effect produced by the burning of the pyrotechnic composition of the conduit-clearing combustible device can be the introduction of direct heat into a conduit or vessel, for example, a sewer line or storage tank, in order to decontaminate explosive materials and their residues 23 disposed in or deposited in the sewer line or storage tank. The sewer line can comprise a sanitary waste line, an industrial pipeline, or a storm water drain. Although the example shown in the drawings relates to a sewer line, it is to be understood that the conduit to be cleaned could likewise be a different conduit or a vessel, for example, an above ground or underground storage tank. The ratio of the components, for example, fuel, oxidizer, and binder, in the pyrotechnic composition can affect the burn rate and temperature achieved by burning the composition. For example, slightly higher ratios of fuel to oxidizer and/or binder can provide higher temperatures and faster burn rates. Fuel to oxidizer weight ratios according to various embodiments of the pyrotechnic composition in the conduit-clearing combustible device can be in the range from about 20% fuel and about 80% oxidizer, to about 70% fuel and about 30% oxidizer, for example, ratio ranges of from 1:4 to about 7:3, from about 1:3 to about 2:1, or from about 1:2 to about 3:2.

Additional materials such as retardants, with or without binders, can be included in the pyrotechnic composition, for example, added to the fuel and oxidizer mixture, in order to reduce burn temperatures and decrease the burn rate. Suitable retardants can comprise non-reactive and/or non-combustible inert materials such as clays, or compounds that decay endothermically such as calcium oxalate. Binders can be used to consolidate the pyrotechnic composition and protect reactive components that are hygroscopic and/or react with oxygen and moisture. Compaction or consolidation of the pyrotechnic composition by pressing the composition into balls, cubes, pills, granules, or the like, can reduce the burn rate by decreasing the available surface area for burning, and can decrease the sensitivity of the mixture to premature burning.

According to various embodiments, the fuel in the pyrotechnic composition can comprise, for example, a solid rocket fuel, or a metal, or a combination thereof. If a metal is used as the fuel, the metal can comprise a metal selected from one or more of, for example, aluminum, chromium, iron, magnesium, manganese, titanium, tungsten, zirconium, and a combination thereof. The oxidizer in the pyrotechnic composition can comprise a material selected from one or more of, for example, a chlorate, a perchlorate, a chromate, a dichromate, a halocarbon, an iodate, a nitrate, an oxide, and a combination thereof. According to various embodiments, if a binder is included in the pyrotechnic composition the binder can comprise a material selected from one or more of, for example, paraffin wax, beeswax, carnauba wax, chinese wax, boiled linseed oil, lithographic varnish, shellac, and a combination thereof. The binder, for example, can comprise a material selected from one or more of bakelite resin, polyester resin, chlorinated rubber, polyvinylchloride, thiokol rubber, epoxy resin, and a combination thereof.

According to various embodiments, binders can be added to the pyrotechnic composition to aggregate, compact, or consolidate the pyrotechnic composition and/or to protect components thereof from reacting with oxygen and/or absorbing moisture. For example, a mixture of an organic solvent and a binder, such as a mixture of acetone and a ceramic powdered binder, respectively, can be combined with a metal powder, for example, FeO₃, to form the pyrotechnic composition. The solvent/binder/fuel mixture can be allowed to dry, whereby the acetone can be volatilized or evaporated from the mixture. The resulting binder-coated metal powder material can then be mixed with other components of the pyrotechnic composition. According to various embodiments, the pellets or granules can be formed before the solvent completely volatilizes, and then subsequently dried. Similarly, the pellets or granules can be made from a solvent and/or binder/fuel/oxidizer mixture. The pyrotechnic composition can be extruded, pressed, or otherwise formed, into pellets or granules and then introduced directly into the flexible hose 32. The amount of binder in the pyrotechnic composition can vary depending on the desired effect, with the amount being, for example, less than 50%, less than 40%, less than 30%, less than 20%, or less than 10%. Polytetrafluoroethylene resin or other accelerants, propellants, or combinations thereof, can be included in the pyrotechnic composition to increase the burn temperature.

According to various embodiments, the pyrotechnic composition 50 contained within the flexible hose 32 can meet the requirements of D.O.T. Explosive Classification 1.2, 1.3, or 1.4. A classification as a 1.4 explosive can be accomplished according to various embodiments, for example, by combining an otherwise explosive material, for example, a D.O.T. 1.1 explosive, with binders and/or retardants, and then the pressing of the composition into pills, pellets, or granules, to reduce the combustive sensitivity of the mixture. The D.O.T. has a broad authority to regulate hazardous materials that are in transport, including the discretion to determine whether the materials should be classified as “hazardous.” Based on the classification of the material, the D.O.T. is also responsible for determining the appropriate packaging materials for shipping or transport. Also based on the material classification, strict guidelines are furnished for proper labeling and marking of packages of hazardous materials offered for transport, and for placarding of the transport vehicles. The necessary requirements can be minimized by converting an explosive material to a pyrotechnic meeting D.O.T. 1.4 requirements, as taught herein.

After combining and/or pressing the pyrotechnic composition into the desired form for introduction into the flexible hose 32, the pyrotechnic composition can be packed, inserted, poured, or otherwise loaded into the hose 32. Suitable flexible hoses and hose materials can include common garden hoses, soaker hoses, hoses made of recycled tires, hollow braided synthetic ropes, hollow braided natural fiber ropes, nylon tubing, silicon tubing, PVC tubing, reinforced paper or cardboard tubing, or the like. The flexible hose can be continuous or sectioned like sausage links after the pyrotechnic composition is loaded therein.

The conduit-clearing pyrotechnic device, including the flexible hose 32 loaded with pyrotechnic composition 50 and ignition mechanism 42, is desirably durable enough to withstand the tension and friction of being dragged through a sewer line, for example, a subsurface sewer pipe or concrete storm water drain line, while being flexible enough to negotiate bends and turns in the sewer line. The ignition mechanism 42 extending through the flexible hose 32 can comprise a device selected from one or more of, for example, an electric time fuse, a non-electric time fuse, black powder, an electric squib, a rocket motor igniter, an electric match, and a combination thereof. The ignition mechanism 42 can be selected and arranged within the conduit-clearing pyrotechnic device such that ignition of the mechanism causes deflagration along the entire length of the device 30 as opposed to burning slowly from one end to the other of the device. The ignition mechanism can be adapted to cause ignition of the pyrotechnic composition along the entire length of the flexible hose 32 and over a short period of time, for example, a period of time that does not exceed 10 seconds, 5 second, or 2 seconds. Deflagration can be defined as a chemical reaction that moves rapidly through a pyrotechnic material and releases heat or flames vigorously. This can ensure that the entire length of the conduit or vessel is decontaminated in the event of a shock wave created by an unanticipated detonation of explosives contained on or in the inner wall of the conduit or vessel. Such an ignition mechanism can also reduce a risk that part of the conduit-clearing pyrotechnic device is not ignited, for example, due to a void or interruption in pyrotechnic composition 50 contained within the flexible hose 32.

According to various embodiments, a method of cleaning a sewer line or storage tank is provided that can comprise placing a conduit-clearing pyrotechnic device as described herein in a sewer line or storage tank wherein the sewer line or storage tank comprises an explosive material deposited in or on an inner wall thereof. As shown in FIG. 2, the conduit or vessel is depicted as a sewer line and the inner wall 20 of the sewer line 22 can be porous to a degree that enables explosive material to be deposited in the inner wall 20 as well as on the surface of the inner wall 20. The sewer line 22 can comprise a concrete material. The explosive material in and/or on the inner wall 20 of the sewer line 22 comprises a break down temperature, and the pyrotechnic material can be burned to achieve an inner wall temperature at or in excess of the break down temperature of the explosive material. The break down temperature can be maintained for a time period sufficient to break down the explosive material. The method of breaking down the explosive material according to various embodiments can comprise a process selected from reduction, combustion, deflagration, oxidation, pyrolization, degradation, decomposition, or any other change in the chemical structure of the deposited explosive material.

The method of cleaning a conduit or vessel can comprise pushing or pulling a conduit-clearing pyrotechnic device 30 into a conduit or vessel, for example, into the entire length of a sewer line 22 to be cleaned. The conduit-clearing pyrotechnic device 30 can be positioned in the sewer line 22 at a location where explosive materials are deposited in and/or on the inner wall 20 of the sewer line 22. As shown in FIG. 2, the ignition mechanism 42 can be accessible at one end of the flexible hose 30 and can pass through a first end cap 38, while the opposite end 40 of the conduit-clearing combustible device 30 can be closed off with a second end cap 39. Ignition of the ignition mechanism 42 at the exposed end results in burning of the pyrotechnic composition 50 within flexible hose 30 at a rapid rate along the entire length of the flexible hose 30 in a direction toward end 40 such that heat is generated by the entire length of the conduit-clearing pyrotechnic device 30 sufficient to break down the explosive materials deposited in and/or on the inner wall 20 of the sewer line 22. Similarly, the method can involve positioning a conduit-clearing pyrotechnic device as described herein in another type of conduit or in a vessel, for example, in an above ground or underground storage tank.

Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the present specification and practice of the present teachings disclosed herein. It is intended that the present specification and examples be considered as exemplary only. 

1. A conduit-clearing pyrotechnic device, comprising: a flexible hose; and a non-explosive pyrotechnic composition disposed within the flexible hose, the non-explosive pyrotechnic composition comprising a fuel, an oxidizer, and a binder.
 2. The device of claim 1, further including an ignition mechanism adapted to ignite the non-explosive pyrotechnic composition.
 3. The device of claim 2, wherein the ignition mechanism comprises a device selected from one or more of an electric time fuse, a non-electric time fuse, black powder, an electric squib, a rocket motor igniter, an electric match, and a combination thereof.
 4. The device of claim 3, wherein the ignition mechanism extends along the entire length of the flexible hose and is adapted to cause ignition of the non-explosive pyrotechnic composition along the entire length of the flexible hose and over a period of time that does not exceed 10 seconds.
 5. The device of claim 1, wherein the fuel comprises a metal selected from one or more of aluminum, chromium, iron, magnesium, manganese, titanium, tungsten, zirconium, and a combination thereof.
 6. The device of claim 1, wherein the oxidizer comprises a material selected from one or more of a chlorate, a perchlorate, a chromate, a dichromate, a halocarbon, an iodate, a nitrate, an oxide, and a combination thereof.
 7. The device of claim 1, wherein the binder comprises a material selected from one or more of paraffin wax, beeswax, carnauba wax, chinese wax, boiled linseed oil, lithographic varnish, shellac, and a combination thereof.
 8. The device of claim 1, wherein the binder comprises a material selected from one or more of bakelite resin, polyester resin, chlorinated rubber, polyvinylchloride, thiokol rubber, epoxy resin, and a combination thereof.
 9. The device of claim 1, wherein the non-explosive pyrotechnic composition comprises a pressed pellet.
 10. The device of claim 1, wherein the binder comprises an organic solvent.
 11. The device of claim 1, wherein the binder comprises acetone and a powdered polymer.
 12. The device of claim 1, wherein the ratio of binder to the pyrotechnic composition is less than about 1:1.
 13. The device of claim 1, wherein the non-explosive pyrotechnic composition meets the requirements of Department of Transportation 2004 Explosive Classification 1.4.
 14. The device of claim 1, wherein the flexible hose comprises a material selected from one or more of a common garden hose, a soaker hose, a hose made from recycled tires, a hollow braided synthetic rope, a hollow braided natural fiber rope, a nylon tubing, a silicon tubing, a PVC tubing, a reinforced paper or cardboard tubing, and a combination thereof.
 15. The device of claim 1, wherein the binder comprises less than about 20% by weight of the total weight of the non-explosive pyrotechnic composition.
 16. The device of claim 1, wherein the binder comprises less than about 10% by weight of the total weight of the pyrotechnic composition.
 17. A method of decontaminating a sewer line or vessel, comprising: placing a non-explosive pyrotechnic material in a sewer line or vessel, wherein the sewer line or vessel comprises an explosive material deposited in, on, or in and on, an inner wall of the sewer line or vessel, the deposited explosive material having a break down temperature; and burning the non-explosive pyrotechnic material to achieve an inner wall temperature at or in excess of the break down temperature for a period of time sufficient to break down the explosive material.
 18. The method of claim 17, wherein the break down of the explosive material comprises a process selected from one or more of reduction, combustion, deflagration, oxidation, pyrolization, degradation, decomposition, and a combination thereof.
 19. The method of claim 17, wherein the non-explosive pyrotechnic material is in the form of at least one of pellets and granules loaded inside a flexible hose.
 20. The method of claim 19, wherein the step of placing the non-explosive pyrotechnic material in the sewer line or vessel comprises placing the flexible hose containing the non-explosive pyrotechnic material inside the sewer line or vessel along a length of the sewer line, and wherein the flexible hose further contains an ignition mechanism therein and extends along a length of the flexible hose.
 21. The method of claim 17, wherein the sewer line or vessel comprises an above ground or underground storage tank.
 22. The method of claim 17, wherein the sewer line or vessel comprises a sanitary waste line.
 23. The method of claim 17, wherein the sewer line or vessel comprises an industrial pipeline.
 24. The method of claim 17, wherein the sewer line or vessel comprises a storm drain line. 